1. Field of Invention
The present invention generally relates to an oxide semiconductor thin film transistor (TFT) substrate.
2. Description of Related Art
A liquid crystal display includes a thin film transistor (TFT) substrate, a color filter substrate and a liquid crystal molecule layer disposed therebetween. There are multiple TFTs disposed on the TFT substrate, and each of the TFTs includes a gate, a gate dielectric layer, a semiconductor layer, a source and a drain. The semiconductor layer may be made of a material including amorphous silicon, polycrystalline silicon, microcrystalline silicon, monocrystalline silicon, organic semiconductors, oxide semiconductors or other suitable materials.
Compared with the amorphous silicon TFT, the oxide semiconductor TFT possesses higher carrier mobility and thus exhibits better electrical performance. However, when an oxide semiconductor layer is formed, a surface of a metal layer, which contacts the oxide semiconductor layer, may be easily oxidized. For example, when the oxide semiconductor layer is formed on the source and the drain, the surfaces of the source and drain contacting the oxide semiconductor layer may be easily oxidized. As such, the contact resistance between the oxide semiconductor layer and the source and drain increases, which s deteriorates electrical performance of the oxide semiconductor TFT. In view of the above, an improved oxide semiconductor TFT substrate is currently required to address the above issue.